So it's a hundred years later and i thought of something else. I noticed the recommendations i gave you could be summed up into 3: colour (red, blue, black, can't believe i tried to list colours e.t.c), design (stripes, graphic, plain, pattern e.t.c) and structure (long-sleeve, short-sleeve, buttons, v-neck, round-neck e.t.c). So you could use these as primary filters and the previous suggestions as secondary filters - nested accordingly.
P.S: I know that "structure of a t-shirt" doesn't sound like a normal thing to say but that's what my brain came up with. So hopefully you understand what i'm talking about and you can change it if you like.
P.P.S: feel free to reach out if you need anything else.