Celebrim, I don't think you're in the proper forums. This is 5th Edition D&D. 5e does not get that complex and there are no "Traits" in this edition.
First, this is the "House Rules" forum.
Secondly, I'm well aware that there are differences between 3e and 5e, which is why I said things like, "I won't try to unpack them all in detail because most of them aren't applicable to 5e or outside of my house rules."
Thirdly, the criticisms I made of the proposed rule still remain valid. The rule has too little variation from existing rules to justify the bloat. The rule does not in fact carry the feel and flavor of something like, "Raised by wolves" or "Raised by apes", well. If you took that as a background, you would not in fact feel like you were playing a young Tarzan type character. Jimbro has said he's looking for something "more specific and deeper", and my criticism is, "This isn't specific and deeper".
The intention in presenting the trait was to give ideas which could be translated into 5e mechanics. Normally, I'd attempt that myself, but with very little knowledge of 5e I don't think my translations would likely be elegant and balanced.
You suggest that the player just ought to be creative and get a background like Outlander to fit, but I personally feel that there are limits to that.
dmnqwk's "Another kind of family." suggestion to my mind at least goes part way toward creating that idea, though even his idea seems a little weak. Tarzan or Mowgli certainly does have advantage on animal handling checks, but he can also handle at least some wild animals as if they were tame, and he can also communicate with at least some animals in their own language. Maybe Tarzan or Mowgli are high level, but at least some of that ought to be available to 'boy Tarzan' or 'boy Mowgli'.
Ideas of that sort, collected together, would I think capture the feel the OP is going for here. Since the advantages conveyed by 'being raised by animals' are probably greater than ordinary backgrounds (being rather magical in nature), it would I think be reasonable if the background also conveyed certain penalties. The 5e'y way to do this might be something like "You have disadvantage on all tool use checks.", which has 5e simplicity going for it while still being very broad.
As for 'animal friend', it seems to me anyone with enough skill in animal handling could have an animal friend of they choose to do so. It doesn't take someone 'raised by wolves' to have a pet dog or parrot. Good mechanics are specific about what they are providing that wouldn't otherwise be allowed.