The main source of information and knowledge is our scriptures, which are many in numbers.
For example- 4 Veda(s), 4 Upaveda(s), 18 Mahapuran(s), 2 itihaas (Ramayan & Mahabharat)
The most challenging thing to prove is the authencity of a scripture or its part.
Nowadays it’s very common for people to reject a scripture or a part of it which seems objectionable to one’s ideology or statement.
The reason it happens is that some people have bind Bhagvan and his associates to certain limits, and they can’t accept Bhagvan doing something which is objectionable to them or the society now.
But let us be honest do we even apply simple logic while saying that Bhagvan is all powerful and at the same time rejecting one of his actions or activity just because it seems objectionable to the society now.
For example child marriage is considered evil now but we do know that Sri Ram performed child marriage with Bhagwati Sita, but we can’t say that the part of the scripture which describes the marriage of Sri Ram, interpolated or added later just because child marriage is evil now.
Thus similarly there are many things which Bhagvan has done and does which may seem objectionable to the so called ‘woke’ and ‘intelligent’ people now.
Also it has become a practice of so called Hindus to seek science’s validation on each and every thing of Hinduism. Such people don’t contain faith on the scriptures
It does not mean that one shall blindly follow whatever is said but it does not also mean that one shall blindly reject a thing just because of the societal thought process.
We shall understand that rejecting a part of any scripture will not falsify any incident that has already occurred in the history
Thus rather than just rejecting or calling any scripture interpolated, one shall try to go deep in study and understand the incident and then come to a conclusion.
If one accepts Bhagvan as all powerful then one has to accept that even if Bhagvan drinks alcohol or consumes meat, he’ll still remain Bhagvan as he is all powerful and paap (sin) can not touch him. Thus rather than rejecting our scriptures just to seek societal support, one shall try to go to a scholar of that particular scripture and resolve one’s doubt.
Thus in my opinion any scripture is not interpolated or later made by any person.