Your little boy is in a crucial socialization period, and if you want to see big differences now is the time to, gently, push his boundaries.
It's quite normal for a cat or kitten who was feral or semi feral to bond most closely to one person and be very afraid of others. They require more time and effort to build trust, and random guests and busy family members just might not have the time, patience, or instinctive body language needed right off the bat.
There's a ton of things you can do though, the simplest and quickest would be for your other family members to each make a point of feeding him - preferably wet food. Wet is better, as far as health for the cat goes, but also it's smellier and therefore more appetizing to the cat. You want him to learn that good things come from people other than you.
Your family members should make a point of spending some time with him, TBH if I were dealing with him I'd put him into one room of the house for the majority of the time to make this socialization much easier on everyone. Your family members could then go into the room and sit with him when they want some quiet time; reading the paper, or a book, watching a tv show, ect. Something where there attention won't be on him and where they'll be sitting mostly still. When they go in they should bring something yummy, like wet food or a bunch of treats. At this stage he needs to get delicious things for simple tolerating their presence. They should NOT try to pet him until he comes to them.
As far as being clingy to you...IMO this is fairly normal, but all four of my cats are quite attached to me. My BF says they orbit me, lol. Whenever I'm home there's always at least two, and generally 3 or all 4, cats within about 10 feet of me. I see nothing wrong with clingy kitties, but you will need to teach him to share.
Make a point of petting him as well as other cats, if he chases the other cat off then immediately stop giving him any attention. Soon he'll learn that only polite kitties get cuddles.
As far as him wanting to 'help' you with everything...good luck! Lol. My boys still have to do everything with me and they're 5! When they were kittens I actually had to put them away in order to get any cleaning done. Now they've settled a bit, but mostly it's constant and calm repetitions of the same thing. "Muffin, out of the fridge. Doran, off the counter. Muffin, you can't climb in the oven. Muffin, get out of the cupboard." Ect. Muffin always wants to go into anything that's open, any door that opens he wants to go through. Doran...loves flour. I literally can't leave my flour container out for a split second uncovered or I'll turn around to find a very happy flour-monster and a HUGE mess. Silly boy.
They have become less insistent about being right next to me...but that could just as easily be me getting used to it and them just being a bit older, TBH. Just calmly reinforce what you want, over, and over, and over, and over. lol. Good luck!