The numbers you want to look at are PDCASS and/or DIAAS scores of each protein source.

I think the part that stinks is all the dead skin sticking to the hair and all the skin oils and bacteria accumulating on that mass.

More variety in your diet is likely to always be superior to less. That goes for both kids and adults. The trouble with younger kids is that deficiencies can impact their development and have more severe long term consequences, and they’re also less capable of seeking out foods to fill that gap.