Dude, this isn’t a sweet 16. Lots of people have tried out multiple times for shows. You don’t just release your work to the world once and then it’s done, you constantly update it with what you’re doing now. No one cares what your abilities were a long time ago, they want to know what you can do for them right now.
Here is a situation that will never, ever, EVER, happen:
Someone says they’re looking for applicants for a job. You submit your work. They say: “Nah, this doesn’t really fit the aesthetic we’re looking for. I’m never going to hire this person and I’m going to make sure to tell all my friends to not hire them too.”
Cut to three years later.
Someone says they’re looking for applicants for a job. You submit your work. They say: “Hey, remember how I’ve seen an infinite number of artists in the past three years? I remember this one specific artist that I passed on because I didn’t like their work three years ago, even though I haven’t thought about that moment since it happened. I see that they’ve improved their work and that it might actually fit the aesthetic of the show I’m hiring for, but I decided three years ago that I’m blacklisting them, so I’m not going to hire them.”
Rest easy in the fact that this doesn’t happen and it will never happen. If it does somehow happen though, it’s good, because I can tell you that no amount of money they’d pay you would be worth working on a show where that’s their attitude.
Also the term blacklist is a bit of a misnomer in terms of entertainment. It’s not actually a list somewhere that every person in the industry cross references and goes: “Oh, I see someone somewhere put this person on a list, I guess I won’t hire them.” Blacklisting is what happens when someone is just an awful person and their reputation of awfulness gets so infamous that every person on their own sort of decides they don’t want to hire them. They won’t hire them because either no one wants to be associated with their awfulness, or they don’t want to put up with it. Everyone has a personal list in their head of people they would never work for, with, or hire, but IMDb Pro doesn’t turn on a frowny face feature next to blacklisted artists.
On you saying you’re mediocre, here’s the thing: I am mediocre. I am somehow tricking everyone at Cartoon Network and they haven’t figured it out yet. I see things that other people do every day that make me go “Wow, that person is really great, I’m not as good as them.” Long Live the Royals is amazing! Steven Universe is amazing! There are a bunch of CN pilots I’ve seen that are amazing! Everyone makes such amazing stuff! The thing is, they also say that about my stuff. They say “Wow, your stuff is amazing! My stuff is mediocre” and I’m like “Why are you so dumb? Why can’t you see how incredibly talented you are?”
That’s because everyone feels this way about their own work. You’re always judging against some ideal in your head. The reason this happens isn’t some humbling/self-defeatist thing, it’s simply because you have more information about your own work than you have about others’ work. You were there when you were brainstorming an idea from nothing. You saw the initial sketch. You remember all the dumb directions you thought to go before getting to your final product. You remember the countless times you redrew a face because it wasn’t smarmy enough. You remember slaving over the exact phrasing of a sentence and whether the character should say “I won’t be coming home tonight” or “I’m not coming home tonight.” You know absolutely EVERYTHING about your work and you can never know that about someone else’s, so you feel yours is somehow inferior.
So what if you’re mediocre? Everyone is! That’s what mediocre means! Show people what you’ve made. If they like it they’ll get back to you, if they don’t they won’t. Some studios might get back to you even if they pass, but most won’t and they’ll just sort of feel guilty about it for a day and then forget all about it.
Either way, make stuff and show it to people, because that’s the only way you’re going to go further. You can’t move up without moving stuff out of your hands and into people’s faces.