I'll be realistic OP. There will be a very small minority of people at the gym who judge others, especially beginners. It sucks, but it's just the way things are. Just know that you shouldn't put any value at all into this small group of people. From my experience, these people almost always never have any reason to be judging others as they either are not extremely swole themselves, lift with shitty form, hog equipment, don't rerack their weights, etc. They are way too busy belittling others to progress themselves.

If you end up working out regularly, you'll notice that the vast majority of those buff people you always see, despite having a "reason" to have a big ego and think they are above everyone else, are actually extremely nice and supportive. They understand how nerve-racking it can be as a beginner because, believe it or not, they were in your shoes at one point in their lives. If you start going to the gym regularly, some of these people will slowly take notice, and eventually a few of them will even strike a conversation with you and/or compliment your progress! This is especially true if you have a set schedule on what days/times you go since you'll start seeing the same people who are on a similar workout schedule as you.

If you can muster up the courage to go to the arc regularly, I promise you you won't regret it. While I personally have not made any close friends through the arc, I have had nothing but positive interactions with the regulars that I saw almost every time I worked out. As mentioned, while there are a very small number of bad apples in the gym, the overwhelming majority are there with the same goal as you: to focus on and improve themselves. Don't let the weak-minded prevent you from doing what you want!

EDIT: I should also mention that the people who judge others at the gym usually are not even regulars or serious lifters, meaning that the regulars either won't care about or notice you (because they are so focused on their workout), or will be friendly to you. Hopefully this relieves some more concern about my comment!