They are not minor gods, but epithets used to describe the same Almighty.
Consider the following mantras from Rig Veda II.1, dedicated to Agni. Agni was declared at BRAHMAN and then AGNI was stated to be all.
तवमग्न इन्द्रो वर्षभः सतामसि तवं विष्णुरुरुगायो नमस्यः | तवं बरह्मा
रयिविद बरह्मणस पते तवं विधर्तःसचसे पुरन्ध्या ||
तवमग्ने राजा वरुणो
धर्तव्रतस्त्वं मित्रो भवसि दस्म ईड्यः | तवमर्यमा सत्पतिर्यस्य सम्भुजं
तवमंशो विदथे देव भाजयुः ||
तवमग्ने तवष्टा विधते सुवीर्यं तव गनावो
मित्रमहः सजात्यम | तवमाशुहेमा ररिषे सवश्व्यं तवं नरां शर्धो असि
तवमग्ने रुद्रो असुरो महो दिवस्त्वं शर्धो मारुतं पर्क्ष
ईशिषे | तवं वातैररुणैर्यासि शंगयस्त्वं पूषा विधतः पासि नु तमना ||
तवमग्ने दरविणोदा अरंक्र्ते तवं देवः सविता रत्नधासि | तवं भगो नर्पते
वस्व ईशिषे तवं पायुर्दमे यस्तेऽविधत ||
तवमग्ने दम आ विश्पतिं
विशस्त्वां राजानं सुविदत्रं रञ्जते | तवं विश्वानि सवनीक पत्यसे तवं
सहस्राणि शता दश परति ||
तवामग्ने पितरमिष्टिभिर्नरस्त्वां भरात्राय
शम्या तनूरुचम | तवं पुत्रो भवसि यस्ते.अविधत तवं सखा सुशेवः
तवमग्न रभुराके नमस्यस्त्वं वाजस्य कषुमतो राय ईशिषे |
तवं वि भास्यनु दक्षि दावने तवं विशिक्षुरसियज्ञमातनिः ||
Translation of Joel Brereton and Stephanie Jamison
- You, Agni, as bull of beings, are Indra; you, wide-going, worthy of homage, are Viṣṇu. You, o lord of the sacred formulation, finder of
wealth, are the Brahman [=Formulator]; you, o Apportioner, are
accompanied by Plenitude.
- You, Agni, whose commandments are steadfast, are King Varuṇa; you, wondrous to be invoked, become Mitra. You, as the lord of settlements
who (offers) a common meal, are Aryaman; you, apportioning at the
ritual distribution, o god, are Aṃśa [/Share].
- You, Agni, (giving wealth) rich in heroes to the one who does honor, are Tvaṣṭar—yours is kinship, o you accompanied by the Wives
(of the Gods) and possessing Mitra’s might— You have given (wealth)
rich in horses as the impeller of swift (horses) [=Child of the
Waters]. You of many goods are the troop of men [=Maruts].
- You, Agni, as lord of great heaven, are Rudra; you, as the troop of Maruts, are master of strengthening nourishment [=rain]. You, as luck
for livestock, drive with the ruddy winds (as horses); you, as Pūṣan,
protect the ones doing honor, in your own person. 402 II.1
- You, Agni, are Wealth-Giver to the preparer (of the offering); you, as the conferrer of treasure, are god Savitar. You, lord of men, as
Bhaga [/Fortune] are master of goods; you are a protector in the house
of him who has done you honor.
- Toward you, Agni, as clanlord in the house do the clans stretch out straight—toward you, the king, easy to find. You, lovely-faced one,
are lord over all; you are the counter(part) to thousands, hundreds,
- To you, Agni, as father, (do) men (approach) with their desires—to you, for brotherhood, (do they approach) with their (ritual) labor,
you who are bright in body. You become the son of him who has done you
honor; you as affectionate comrade—protect (him) from assault.
- You, Agni, as [R̥bhu/] the craftsman at hand, are to be rendered homage; you are master of the cattle-rich prize [/Vāja], of wealth.
You radiate widely [/(are) Vibhvan]: burn through to giving! You seek
to carve up and to stretch out the sacrifice.
Yama, Garutman are subsequent additions to the list above.
In RV I.164.46 it was mentioned that
इन्द्रं मित्रं वरुणमग्निमाहुरथो दिव्यः स सुपर्णो गरुत्मान | एकं सद
विप्रा बहुधा वदन्त्यग्निं यमं मातरिश्वानमाहुः ||
They say it is Indra, Mitra, Varuṇa, and Agni, and also it is the
winged, well-feathered (bird) of heaven [=the Sun]. Though it is One,
inspired poets speak of it in many ways. They say it is Agni, Yama,