The specific amphibians that are our ancestors are extinct, and they would be very different from todays amphibians. I do agree on the size comparison, though many frogs and toads (not neccesarily newts and salimanders) are dangerous to touch because of poisonous skin.

I think it was m,ainly just because nothing but bugs were on land so there was a huge amount of niche opportunities.

with reptiles in between

This evolution helps the species to adapt to the climate! :o

birds are tetrapods because they evolved from reptiles, as with mammals