Summary : The Vedas DO NOT declare Vishnu as a minor deity. He occupies very much the same lofty position as he always has. The verses are not accurately represented, but despite that is to be understood as reference to Lord Trivikrama, Indra’s younger brother, showing brotherly affection for him. There’s no labour involved.
Detailed
Obviously, just like the Puranas, the Vedas too declare Brahman in a similar fashion, the very one for whom all scriptures are supposed to be dedicated. We shall restrict the discussion to only Shri Hari. As per the question there are some ‘apparently’ contradictory verses about him, which we shall sort below.
The Supremacy of Shri Hari in the Rigveda
It is incorrect to say that Vedas do not proclaim Shri Hari as Brahman. One answer already gives the Shadvaishnava verses which show Vishnu’s high position. In addition I’d like to state one more (taken from here):
यः पू॒र्व्याय॑ वे॒धसे॒ नवी॑यसे सु॒मज्जा॑नये॒ विष्ण॑वे॒ ददा॑शति । यो जा॒तम॑स्य मह॒तो महि॒ ब्रव॒त्सेदु॒ श्रवो॑भि॒र्युज्यं॑ चिद॒भ्य॑सत् ॥
Vishnu is the most ancient of all, yet also the most recent. Nothing and no one creates Vishnu, yet Vishnu creates everyone and everything.
-Rigveda 1.156.2
Against the above translation, Sayanacharya’s explanation presents a slightly different and more convincing view. Some words are explained by him:
- ‘पूर्व्याय’ पूर्वकालीनाय नित्यायेत्यर्थः - pūrvāya means ancient and must be understood as nitya (eternal).
2. ‘वेधसे’ विविधजगत्कर्त्रे - Vedhas means the creator of many jagats (worlds).
3. ‘नवीयसे’ नित्यनूतनाय अत्यन्तरमणीयायेत्यर्थः - navīyas means one forever knew, to be understood as extremely pleasing to look at.
4.‘जातं’ जन्म उत्पत्तिं हिरण्यगर्भादिरूपं जन्म - jata means birth in the from of Hiranyagarbha.
In fact, for the very next verse (1.156.3) Sayanacharya explains :
विष्णोरेव स्वर्गापवर्गसाधनाय इष्ट्याद्यात्मना द्रव्यदेवतात्मना वा परिणामम् - Only Vishnu is the facilitator of svarga and moksha, he is the atman of the Yajna and the devata of the Dakshina or (and) the result as well.
Thus we can see that the supremacy of Narayana is upheld by the Rigveda samhita.
Solving the ‘Apparent’ Contradiction
This will be done in two parts. First present a more accurate explanation for the verses quoted in the question, as per Sayanacharya. Second the reason for contradiction.
A. Sayanacharya’s explanation for the verses
From the below it will be seen that while giving a fairly accurate translation, how the verses in the question have been misrepresented in their titular summary.
- Rigveda 2.22.1:
The translation in the verse quoted says Indra drank (the poured out) Soma with Vishnu, yet the title wrongly says he pressed Soma for Indra. As per Sayana too there’s no pressing (labour) by Vishnu. He simply says:
तं सोमं विष्णुना सह अपिबत् - he drank that Soma with Vishnu.
- Rigveda 6.17.11:
In the very same translation quoted, the verse talks about a certain ‘he’ who has cooked buffaloes. That same ‘he’ together with Pushan and Vishnu poured 3 vessels of Soma for Indra. Thus this ‘he’ cannot be Vishnu who cooks. If one sees the previous verses, it’s amply clear that this ‘he’ is Tvashta (explained by Sayanacharya as devatas architect). Although little confusing, Sayana too says, ‘may he cook’ in singular form (पचेत्) and hence can’t refer to all 3 but only Tvashta. There’s no cooking of beef by Vishnu. Vishnu pusha Tvashta only pour the soma. Though little out of order, he says these 3 fill 3 vessels of Soma:
सोमैः पात्राणि पूरयन्त इत्यर्थः - they fill the 3 vessels with Soma.
Rigveda 8.15.9 of the devatas praising Indra is correct, even as per Sayana Bhashya
Rigveda 8.66.10 quoted above doesn’t match with Sayana’s 8.66.10 of the Rigveda. Hence not commenting. But let’s assume it’s true (it’ll be sorted below).
Thus we can see some claims made are not accurate, not even matching with the same translation given against it.
B. Explaining the ‘apparent’ contradiction
Though the claims have been proven inaccurate, the question still remains, why is Vishnu (declared supreme in the Rigveda) drinking Soma alongside Indra and why is he pouring him? Does the same person, whom the same Rigveda declares as eternal, do this?
The answer is, ‘Vishnu’ has a dual meaning - Narayana as well as Trivikrama. The person who’s pouring the soma is to be understood as Vishnu in the form of Trivikrama, the son of Aditi and Kashyapa and Indra’s younger brother, and not in the form of the eternal God. Proof of this is from the Rigveda itself. Please see the Shadvaishnava verse 1.22.17 and Sayana’s explanation:
इ॒दं विष्णु॒र्वि च॑क्रमे त्रे॒धा नि द॑धे प॒दम् । समू॑ळ्हमस्य पांसु॒रे॥
Sayana says- विष्णुः त्रिविक्रमावतारधारी ... जगद् ... विशेषेण क्रमणं कृतवान्। तदा त्रिभिः प्रकारैः स्वकीयं पादं प्रक्षिप्तवान्। सेयमृक् यास्केनैवं व्याख्याता - विष्णुर्विशतेर्वा ... यदिदं किंच विक्रमते विष्णुस्त्रिधा निधत्ते पदं...।
Vishnu in the form of Trivikrama transgressed the world. Then he cast his legs in three different ways. This Rik has been explained by Yaska - Vishnu the one who pervades or the one who transgresses (pervades) the world, while placing his feet in 3 ways.
We can see that Vamana is also called Vishnu not merely because of being Narayana, but because he became so huge that he pervaded bhu bhuvah svah. In this case, it doesn’t mean Narayana who pervades all creation and hence called Vishnu. The word ‘Vishnu’ carries a dual meaning.
These words of the Veda and the relation between Indra and Vamana can be further explained from the Harivamsa. In the Govardhana episode similar to the ‘apparently’ confusing Vedic verses, Indra too first acknowledges Narayana as of higher position than him, but is quick to go back to Upendra. For example:
[praising as higher] Krishna, all the creations of this world are in your body. This is as per the direction of brahma. You are among the gods , like gold in minerals. Even the self manifested brahma, with his knowledge and position, is unable to understand you, like a lame man who is unable to catch up with a fast runner.
Vishnu Parva verses 19.23-24
[Back to Upendra] People on the earth will worship mahendra (me) and upendra (you) with flags and sacrifices.
-Vishnu Parva verse 19.58
The above (first declare as supreme then younger brother) is because, though Indra knows who Vishnu is, yet he considers him as a younger brother (Harivamsa 2.19.37) and expects the same the same respect a younger sibling will give the older. This can be seen from Indra’s words when Krishna wants to take the Parijata from him, an event subsequent to Govardhana (where Indra himself acknowledges Narayana as higher than himself). You can find it here.
Therefore even the explanation for the Vedic verses is the same simple one. A younger brother Vishnu Trivikrama is respectfully praising the older and both are drinking Soma together with brotherly affection, even one pouring some of it for the other.
Conclusion
To answer your following question:
Is it true that Vishnu is a minor God in the Vedas, who later became a major God? If no how do you explain the verses mentioned above and how do you establish the supremacy of Vishnu in the Vedas?
The Vedas mostly extol the residents of svarga and Vishnu as Trivikrama (being Indra’s younger brother) is included among them. However besides being included as Trivikrama, he is also supreme and eternal in the same Veda. How can someone described as eternal, be only a minor deity?
The verses as stated are grossly misrepresented in the question. After deriving a more accurate meaning, they can be explained as the brotherly respect and affection shown by Vishnu playing the role of Trivikrama, Indra’s younger brother.
Extra Note: It is pertinent to note that the Vedic samhitas extol the residents of svarga, more than Brahman since through the Karmakanda (yajna) portion they get their nourishment. Hence in almost all places, the names belong mostly to the Adityas (Vishnu included), Vasus like Agni, Vishvedevas, Ribhus and such heavenly residents. Hence the Vishnu included in these lists is Trivikrama Vamana. If the supreme gods were to be shown as serving Indra, why are Rudra and Hiranyagarbha not included with these devatas? Because they did not incarnate among the Adityas. Vishnu incarnated and hence Vamana is included among the 12 Adityas. Where he’s spoken of as Brahman, he’s Brahman and not these devatas.