I really love your tank! And your enthusiasm and wanting to learn is awesome to see too, love seeing people like you entering the hobby!
You definitely should enter! I've entered a few times with no expectation of winning, and I don't mind at all if I don't win, it's only for fun! I did win once, and was so surprised since there are so many beautiful tanks in the forum, but it's important not to be intimidated by that, and just show what you've done already! Every tank is an evolving environment. It changes over time, plants get established and grow, you change up the substrate or hardscape and take some nice photos (my tip is to clean the front glass inside and out first! Watermarks and algae can make it really hard to take good photos!)
So even if you enter and don't win, you start seeing things you'd like to improve for the next time, or can always ask people for feedback, like you're doing now! There's no punishment if you don't win, and if your fish are healthy and you're maintaining it, your tank isn't "less than" someone's beautifully aquascaped, all natural CO2 injected tank. It's just a different style of fishkeeping, and we're not doing full on aquascaping contests here! Just our everyday tanks that we love
DO IT! lol

It also just makes you more involved in the forum, you know? I was super nervous before I entered the first time, thinking I didn't stand a chance. I remember that I pm-ed
@Fishmanic some photos before entering asking if I should enter or not, and feeling like I couldn't compete, and said that exact thing to him! He was very patient and reassuring, lol! Then teased me because I was so surprised when I won, lol! You never know, and it's a nice way to get to know people here and see each others set ups. I know I've drawn a lot of inspiration and ideas from other tanks and hobbyists here.
Your tank - I'm not wild about the gravel colour, but I admit that I'm biased towards a natural look, and I also hate when people get snobby about not having anything fake in a tank! If you like the gravel colour, then keep it! That one isn't doing any harm to the fish you're currently keeping.
You also don't have to have just fake, or just live! You can do a mix of both, and I've seen some stunning tanks with both! Like
@Fishmanic said, you can get some really good silk plants too, with some wild colours that really pop, and can look awesome when dotted around the real live plants!
I'd definitely add some larger pieces of driftwood though, since you have plecos. They do need driftwood, and they appreciate it as hiding spots and territories. For some reason, with that background, I'm mentally picturing some taller larger wood pieces sticking up... maybe
@Wills would have better suggestions, he's got a really good eye for aquascaping!
I wouldn't remove any of the live plants except for propagating or moving to another tank. There's lots of room for live plants! I'd remove the fake ship and/or big stone thing personally if it comes down to needing room, since they take up a lot of space, but if you like them, keep them!