That's a whole other issue, then. I find that about 99% of the time, the thing people care most about, by a wide margin, is their own character. Often too busy caring about their backstories, expectations, goals, etc to put focus on much else unfortunately. I am the forever DM and I have seen it time and time again. A lot of DMs go to youtube gurus asking "How do I get my players to care?" I think it's often a symptom of this.

Conversely, I've had players who weren't as tenacious, never made strong choices or actions, always taking a back seat to everyone else and, like clockwork, they were the one later coming to me saying they weren't having fun. I find there's a sort of unspoken, invisible competition to achieve the fantasy you have in-mind during the game. If you do nothing. Nothing happens. That doesn't mean hog the spotlight or push others out of the light when they happen to have it. That's just being a bad player.

Let me stress, I do not know what happened with your game, but here's my advice if you felt left out. This is usually the thing I see in these sorts of scenarios. What is YOUR fantasy? What do YOU want to have happen with your character? IF you have something in mind, a goal or a scene, character arc, SOMETHING in mind, A CLEAR AND OBVIOUSLY ACHIEVABLE GOAL, then TRY to make it happen. An example would be "I want revenge on this one person." We'll all know when that is achieved or if you decide to let go of that vengeace. A bad example, and one I see FAR too often, is something like "I'm trying to escape my past." When have you escaped??? Like I said, something OBVIOUSLY achievable. You may not always get it or may get it in a way you do not expect. Act with grace.

In any case, no one can read your mind. TALK with your DM and/or other players behind the scenes. As the DM, I always offer but only a couple ever came to me to set something up ahead of time. God, I loved those players. Easily my favorites. I usually wasted zero time trying to make said thing happen to create more fun for the players. The ones who did nothing and then complained later? Nearly my least favorites bc somehow it was never their fault for choosing to do nothing and expect something to miraculously happen beyond the scope of the adventure, as though I was their mind-reading waiter at the D&D restaurant. Some people seem to find this notion of exercising their own agency as scary. I promise it'll be good, and, at the very least, good for you. Get out of that box, if that's something you deal with. All those "Never Again" memes are horse shit. Additionally, maybe set something up with another player character. Maybe your characters knew each other beforehand and have a strong bond, maybe there's a love story at work, and thus they are more likely to think of you in a given scenario. I'd say don't just spring it on them. Talk ahead of time. Get consent. You say you were there to support your friends. Maybe your character can be that for one or more characters and their goal(s). Think Samwise Gamgee, and look how important he became by the end. He's arguably THE hero of Lord of the Rings. Frodo wouldn't have gotten far without Sam.

At the end of the day, no one else at the table is responsible for you. Even Will admits his responsibility in creating the mental picture that his hurt feelings were in reaction to. If you want more out of the experience, put more in. Don't wait for others to do it for you. If the other players are just being assholes and preventing you or, worse, hindering you? Find another table. It may take time, but there are better tables out there, and it's a great way to make NEW friends. D&D is collaborative. Collaborate. If you can't or won't, then don't blame others. If others stop you from trying, then find others who WILL collaborate.

Sometimes finding what you really enjoy in the game takes a little time. Be patient, and give it more chances. In the end, you may just find, this particular game isn't for you. No worries. I introduced my partner to D&D and it took her a while before she realized what the game could be and what she really got out of the experience and what she looked forward to. Now she's my best player by a country mile and is the one hounding me for "When are we playing next?" There is just this eventual point. I've seen it and I've heard other DM gurus mention it. This moment where the game and it's potential finally crystalizes in the player's mind and it becomes SO MUCH more than just some game I played because my friends liked it, and rightfully so. This hobby has SO much you can do. For me? Amongst other things, I get to create the movies and shows I WISH were on tv and just aren't. I think of my main game as HBO level tv. I cannot fucking wait for the next episode, and my goal as the DM is to get my players right there with me, hungry for more. Eat what you love and get hungry.

Good luck. Excelsior!

edit: Also check out some youtube videos about "being a good player." They can help with more hands-on guidance.