Okay, to be blatantly honest, all these designs are okay-ish. It still looks like a low-tier T-shirt. The design could be WAY better, like you could write something on the sleeves, and make the T-shirt look more interesting enough for a stranger to look at the T-shirt and go like, "Wow, I like this T-shirt". The current humor or"memes" used on these designs aren't as good. Right, the t-shirt looks like someone took a plain T-shirt and added some images from google on the t-shirt, and that's it.

Also, have you considered selling not just T-shirts, but hoodies, tank tops, crop tops, sweatpants etc?