So God didn't necessarily "reveal" religions to man, but man "revealed" or brought the concept of an invisible all-knowing God to man? And then when someone asked, "Prove it? Prove this invisible God is real? They answered and said, "What do you mean prove it? We just told you that God said it. If he wasn't real, how could he have said it?"
Gods/Goddesses/Allah are fictitious entities created by human imagination. How can they reveal anything? And, when they are supposed to have revealed, it should be taken as coming out of the mind of that person who is claiming a revelation. You are correct when you say what I have underlined in your post.
In Hinduism, people debated the things which they did not understand. Had differences. Some believed one thing, some the other. Students did not necessarily ditto the teachers line all the time, you have examples of Yajnavalkya and Buddha. These views constitute the "Upanishads" and "Darshanas".
* "The Sanskrit term Upaniṣad (from upa "by" and ni-ṣad "sit down") translates to "sitting down near", referring to the student sitting down near the teacher while receiving spiritual knowledge." Wikipedia - Upanishads.
* "The term (Darshana) also refers to six orthodox schools of Hindu philosophy and their literature on spirituality and soteriology." Wikipedia - Darshana
Literally, Darshana means seeing, view, opinion.
So the 4 Vedas, these 13 or 14 main (old) Upanishads and 6 Darshanas form the basis of Hindu thought. Nothing revealed, all researched, debated and peer-reviewed.
Why are you surprised that people question its validity? Too many things don't make sense.
Yeah, not much sense. To some,
it is said, God sent Gabriel, to others the 'Maid of Heaven'.
It should not depend on 'individual perspective'. We should see if there is any evidence of what we believe or otherwise change our belief according to evidence. What is the quandary about this?
That is what happened in my case. I did not find any evidence for Gods and Goddesses in Hinduism or for soul, heaven or hell. So, I changed my belief to atheism and science. Fortunately, I did not face any problem because atheism had always been a part of Hinduism (Nireeshwaravada).
In some ways your position has similarities to the well known atheist and critic of Christianity, Richard Carrier who denies any evidence for the historicity of Christ.
What is in question is not the historicity of Jesus but his divinity. Son of God in his case, being a beloved prophet of a supposed God or Allah, or being a messenger/manifestation/mahdi in case of others. Even if Moses, Jesus, Mohammad, Joseph Smith, Bahaollah or Mirza Ghulam Ahmad may have been historical, that does not give them any 'divine' authority.