After a few weeks of confirming its fondness of cat food, I trapped it in a cage with cat amenities, tried to pet it and got bitten.
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Scared and alert fluffy black cat on a perch in the upper corner of a big cage, at eye level with me and camera
Probably a question of time and patience. My advice would be to be in its' company but don't push space boundaries. E.g. be in the same room doing your own thing, maybe sometimes speak to it, look at it and slow blink and just carry on with your own life.
Offer food and treats in your company (same deal, give food but stick around in the room, but give it space). Sit a lil bit closer to it over time to build trust but avoid initiating touch. Try to play (like string on a stick or something similarly simple), some cats value playtime over food. One of my cats values just being stared at over both food and play, they each have their own preferences - once you figure it out it'll be a lot easier.
Eventually it'll learn to trust you and associate your presence with food and play.
Just be aware that it may take weeks or months to build a bond, although if you aren't seeing any improvement at all (like cat is tense when you're around, even from a distance, reluctant to eat when you're near etc) in 2 or so weeks time then the method isn't working and you gotta try something else.
Good luck, and thank your for caring for it!
This is the way, when we have new kittens or cats that are on the property and have been using the food, water and seeing the others go inside. I just go out near the food area (like 10 to 15 ft) and just watch youtube, read the internet, dont look at them for the most part. When they come up I look, slow blink at them and go back to what I was doing (from my understanding this is like hey I saw you, dont view you as a threat and you are welcome in my space). Some times its 30 min when they sniff me or a few hours. It helps a ton if you have other cats that are known to them (we have a lot of near by strays and barn cats that know us), and they will be like oh hey your on the ground wanna cuddle or give pets! It really lets them see like well they are cool, maybe I can get a bit closer.
Once they are in range of petting, RESIST!!! Let them get like a foot away and then offer a hand for sniffs. Go SLOW, if they start to move back, withdraw or hold, if they dont bolt and you held it there they might lean in, once they lean in you can wait and judge or try to offer a pet. Work it from there. Best of luck, they look like a great one, I love the round face!