The experience using the development environment of Unity/Godot/Unreal is completely different than Cocos2d. Coding in Cocos2d requires you constantly be reading docs, hunting across the net for examples because the docs are horrendously incomplete and outdated, and doing all the coding and asset management by hand. There is a studio editor for Cocos2d, but it is difficult to use and the documentation for it is limited. I never managed to get it to work. Part of the problem is that much of the development of Cocos2d takes place in Asia, so the docs need to be translated to English. By the time this happens, they no longer represent the current state of the library.
If you try making a simple loading screen and short game in Cocos2d compared to Unity/Unreal/Godot, you will instantly see how very different the two are. The learning curve for Unity-like development is really low. You can start on your game immediately and learn as you go. Cocos2d has a huge upfront learning requirement, and it's hard to pass because of the state of the docs. Frankly, I'm surprised at how many games are made in Cocos2d given the other offerings that are available which include a strong development environment. The biggest pluses to Cocos2d to me are that it's 100% free and that it has great crossplatform capabilities. But when you consider how much more difficult it is to use, and the fact that your game is unlikely to ever make money or cross the royalty threshold, you probably should be using an easier tool that is more popular and might lead to job opportunities. A lot of great engines are offering a free-to-start-with option: Unity, Unreal, Marmalade, Corona, GameMaker, Shiva, Stencyl, Construct2. Many of these didn't use to have a free option other than a 30-day trial.