Pretty much all plant matter contains some protein or amino acids, unless you are using the oil of the plant. Aloe vera (the plant) does contain many amino acids.
I have issues with many proteins, wheat being the worst, but I do well with aloe.
I have wondered if the flash drying that some get with aloe is due to the amino acids.
They aren't strong proteins, so aloe is often found in ingredients that are considered to be protein free. But, for those who can't take large doses of protein, it doesn't hurt to track how aloe works for them. It's very much YMMV; what works for one won't always work for another.
Some notice the same thing with hops.
Med/Coarse, porous curly.