And therefore ...
Any race would be explained simply by stating: They kidnaped me aswell.

Agreed.
But how the world reacts to them is different than a monster race.
Gale is just a human inside out. So is Wyll.
Shadowheart? Your normal half-elf from next door.
Astarion is just a pale elf, people don't expect a vampire in broad daylight.
I imagine a gith would get some rised eyebrows but they don't interact as much with this plane to people to react in any special way.
A yuan-ti? People sure do know them or at least heard stories about them, no way they would be permitted to enter any civilized places other than at the tip of a guards spear.
That's what would be expected and I don't expect Larian to possess the right means to do it properly - thus they shouldn't do it at all.