I feel you, OP. Online dating is a surefire way to destroy your self esteem, especially if you're a guy. I made the mistake of getting back on dating apps after a relationship where I felt undesirable and unattractive in because if you want to feel those two things, there's nothing better than online dating to feel like no one wants you.
This is exactly why online dating as a guy is such a frustrating ordeal. Speaking strictly from a guy's perspective, it feels like you need to make your way through a textbook's worth of steps and do them perfectly to even have a chance at a date. Most women I encounter on apps are incredibly fickle. You can do the things you list above but any little thing can cause the person to completely lose interest even if they seemed completely invested a moment before. There's almost a Goldilocks logic to it: if you message them for too long, they'll get bored but if you ask them out too quickly you come on too strong. You conversation can't be too shallow but it also can't be too deep, your messages can't be too short or too long, you have to show interest but not too much interest, you have to be funny but not make too many jokes, etc. I've tried to approach people in every way I could think of but it just never seems to work and I wonder why they even matched with me.
I feel the role guys often have to play is that of the court jester; trying to entertain royalty who will send them away at a moment's notice if they are not constantly providing entertainment and distraction. On dating apps, you're juggling balls, smashing pies in your face and jumping around goofily like "look at me! look at me!" just to hold their attention long enough to ask them out on a date or get their number. You mentioned always ending your responses with another question so they will respond and it just reminds me of how much you're required to guide the ship. So many women will say in their bios "please know how to carry a conversation" yet you need to hold their hand through the entire interaction, leading the conversation and making sure to hand them easy follow ups. Even then, I'll ask very open questions that you can't simply answer yes or no too and yet I'll still get like three word responses and nothing for me to go off of. In the end, I feel like I'm doing all this work. I feel like I'm trying to prove my worth and sometimes it's just like "what do you have to offer to this?" And of course, we both realize that they don't have to offer anything to find interested people. There's always another guy messaging them that could be more interesting. I guess that's just the dynamic. There's more guys than girls on the apps and like you said it's highly competitive so guys have to sell themselves and that's often a very frustrating and humiliating process.