Vedanta and Purva Mimamsa believe that the Vedas are unauthored. Nyaya believes that the Vedas are authored by Ishvara.
What do other sects believe? Is there anyone that believes that the Rishis authored the Vedas?
Here are some verses:
RV 1.61.4: asmā idu stomaṃ saṃ hinomi rathaṃ na taṣṭeva — “For him, I design this hymn, just as a carpenter designs a chariot”
RV 1.77.1: kathā dāśemāgnaye kāsmai devajuṣṭocyate bhāmine gīḥ — “How shall we offer to Agni, what kind of words should we say to him the bright one, which will be divinely acceptable?”
RV 1.94.1: imaṃ stomamarhate jātavedase rathamiva saṃ mahemā manīṣayā — “This stotra we make for the most sacred Jātaveda with deep meditation, just like building a chariot”