Jai Srimannarayana!
Buddhism, though originally founded by Siddhardha for peace and non-violence, but at a later stage, people following started turning too violent, eating raw meat, even today we can see that. Anything that moves could be taken by them as food. That is one of the reasons.

Next reason is, they did not accept Vedic tradition as authority. If one does not accept vedic tradition, then there would not be any history to the nation left behind. People of this land accepted the history of Rama & Krishna etc., as their own. But when that was denied, they did not take the Buddhism to their heart. So we are vedic people.
Unfortunately, today this fact is in need to be understood.
=chinnajeeyar=

Interesting questions you have.

Q) Did Ravana actually have 10 heads or is it an allegorical meaning ?
A) Ravana was having 10 heads. Though they were interpreted as 10 indriyas or organs of the body like sensory and vital organs, yet he was really also was having them.

Q) Which Treta Yuga did it take place ? I have heard it was in the 24th treta yuga.
A) 24th trethayuga was the rama’s period. Right you are.

Q) Are Vanaaras, Rakshashas, etc are humans with different qualities or they actually different living entities?
A) Vanaras were having ability to have their own chosen from. Ka:maru:pa Dha:rana: sakthi. So they can take any form they want.

=chinnajeeyar=