This is imposter syndrome and literally everyone at every level experienced it at one point or another.
First, it is very bad (I might say, the baddest) to approach science as a competitive endeavor. Science ought to be collaborative, especially in the same group. If the professor is critiquing you it’s because he wants you to do better. If you are having personal issues and can’t handle the pressure then maybe this isn’t the right job or the right time for you. That being said, just try to relax and know that the bar for you is not really that high but clearing it requires you to make a genuine effort. Learn from the people that are better than you in the group.
My first semester I felt like I wasn't smart enough or good enough for almost all my classes and it was a struggle but I just worked harder so that I could succeed. I had no idea what I was doing in lab courses as it was my first time doing that type of thing. I've been in a research lab now for almost 2 years now and I'm still learning new things I didn't know before or refining techniques etc. Don't let it get to you how others are doing. That doesn't matter. Just try your best.
So if this guy didn’t care about you he would either just ignore you or get rid of you. Why would he spend his time trying to help you improve if he didn’t care? I wouldn’t look into this too much.
I’m assuming you want to be a physician at the end of all of this since you’re posting here. I’ll be blunt: you need tougher skin and more self confidence. You got this lab position right? So own it. Go in there with a positive attitude and do your best. Nobody is going to carry you into med school. You have to walk the walk yourself. If you constantly doubt yourself and your abilities you will just become a self fulfilling prophecy of failure.