Am I desensitized If I think that Gary the Stormtrooper is funny?

Not necessarily. A lot of such stuff (Adult Swim in general) has a similar type of humor and certainly I have many sensitive friends that get it and think it’s pretty hilarious.

It might depend on what parts you’re laughing at, and in what way you’re laughing at them.

Some of this type of humor actually exposes how much the material it satirizes is in denial, by going where the original material doesn’t. I think the Ewok part here is a great example. The Ewok/stormtrooper battle in Return of the Jedi is crazy in its denial of the situation it shows, by having “a legion of [the Emperor’s] best troops” be overpowered by a bunch of muppets, with IIRC only one muppet being shown dying, and oh how sad (yet sanitized) it was… but that only works because most people prefer that to seeing how many dead, dying and maimed people and muppets there would be in that battle. There’s no freakin’ way only one Ewok died. By showing some of the reality and horror of violence, it exposes that whole cover-up, and makes you see the ugliness of violent murder – it’s evokes humor because it’s so horrible.

On the other hand, if you’re a nasty McNasty, you might like that scene in a sadistic way, in which case ya you might (also?) be desensitized.

But I imagine from the way you’re asking, that no, you’re not.