I also feel that my site doesn't fit in visually with those of most people here. As much as i like the asthetic of many of these sites, i also appreciate simpler text-focused stuff. It's easier to write, easier to read, lighter weight, more accessible,..
And it feels authentic to me. It's not flashy but it tries not to be too hard on the eyes, and all the interesting bits are in the text. They're there for anyone who knows English to read, but you have to find it and read it yourself. It won't jump off the page at you. If you meet me in Reality, i think i'm pretty boring and unassuming before you get to know me or get me talking about something i care about. There's stuff here, but people have to dig a little for it. My website is the same way.
If you copy some code to your site (no shame, like Cele said it's the core of coding) and don't like how it looks or feels, don't keep it. Delete it or change it until you do like it. If you're using a layout or theme that someone else made (or even one you made) out of some obligation to fit in and not because you really like the layout or theme, that might bother you for as long as you leave it in your pages. And who is that sort of thing for on your site if not for you⸮ If it's just there for you and you don't like it, you don't have to use it.
Also, i think the idea of fitting in doesn't fit in here as much as in some other spaces. One of the beautiful things about having your own website to put things instead of an account on some social media platform or forum is, it doesn't have to look the same as everyone else's. The Melonland Forum lets you customize your profile page with CSS, but most sites don't. On most sites the only visual difference between your profile and someone else's is a profile picture, maybe a banner, and of course the text. Your website can be as different from anyone else's as you can imagine and code.
So what does fitting in mean when all our sites look and feel different⸮
Fitting in and feeling authentic aren't the same thing, at least not to me. I don't know what it means to fit in in a space like this. I don't think i can tell you exactly how to make your site feel authentic to you. My best guess is to try stuff and see what you like. If you have an idea, write it down and then do your best to implement it. See how it goes. Worst case is it doesn't work and you can learn something from that failure. Best case is you love it and integrate it into your site, and everything is better for it.
Maybe i'm misunderstanding what you want here. Maybe you are just asking what the process is for making a website on the more concrete, mechanical side than the feeling-good-about-it side. I've found it hard to articulate the difference before, and that can make finding help with one side hard when people assume you mean the other.
I started learning HTML from a copy of HTML 4 For Dummies. It's an old book, but most of the information in it still holds up. Now i mostly get coding help from
Mozilla Developer Network or
W3Schools, or if i know a specific web page that does what i want my own to do, i look at its code. I find basic HTML pretty easy. Some CSS is fine too. Javascript i've yet to need so i haven't learned or used it yet. I don't know how helpful this paragraph is for how long you've been online and doing stuff with the Web.
For graphics, what tools i use depend on what i need. I do a lot of stuff in GIMP. It's primarily a photo editor, but it's also fine for pixel art. Krita is better for higher resolution digital painting. Blender is good when i need a 3D scene or object and i want all the angles and shadows to make sense. I don't yet know a good way to optimize my images. GIMP isn't great for this, so currently my images are just kind of big.
And people here are happy to help. You might not always get a response to your question quickly, but it's often easier than trying to find help on Google and Reddit for specific problems.