Actually I've never felt worthless, I just feel

sub-human.

I feel like some alien species between human and, say, cat.

Humans universally look down on me. Because I had head injury so I am slow.
Especially slow of speech. Slow to make decisions. Truly, this makes me sub-human.

But my five cats look up to me.

Okay, sometimes it's embarrassing, how much their esteem means to me.

But I'll take what I can get. In their eyes I definitely am not "worthless."