Hang in there.
By disrespectful, do you mean they say mean things to you?
Or do they go for Falcon Punches off-stage?
If it's the second one, don't take it personally. They're just going for fun stuff.
If it's the first one, what's the context if I may ask? I don't wanna give intentionally-good-but-turns-out-bad advice.
For me, people are neutral or nice. And yes, I'm a noob.
Can you ask your opponents for tips?
e.g. someone told me I should move more in neutral, so I did that and then he said I was doing better.
Mixing up your approach could make you less predictable
e.g. switch from attacking right away to waiting a bit before you attack.
sometimes hold your shield a bit longer.
throw in some spot dodges, rolls, full jumps, grabs, etc.
One mentality that helps me is to aim to lose, learn and have fun.
Because you're gonna lose a lot early on.
But if you're not trying to win, then you don't get upset when you lose!
Learn what you can and practice, and you'll improve.
It's working for me.
And hey, even players who destroy me lose to the better players in pools.
Good luck!