Is it rude to say “Hey” without mentioning the name of the person I.e: hey Jason, when sending a text ?

Not if it's a friend/family. If it's someone you don't normally text or talk to often then I would use their name

It used to bother me on phone calls. I say "Hey" back to them, say "Hello?", or say nothing. I just ignore it on texts.

In a text, I don't see the necessity of including a name. Texts are informal usually.

If it’s someone I personally know, I always say their name.

Noooooooo