Is WordPress Right For my Website?

Hey guys,
I just took on a development job and need some help deciding what the best platform might be to go about building the site on.
First, as far as my skills go, I am comfortable programming and have experience in mainly JavaScript, JQuery, CSS, and HTML but have yet to dive into any PHP. Also, I have never built a site using WordPress so I am unfamiliar with its intricacies and quirks. So with that in mind hopefully you guys can give me some advice on whether wordpress is right for the job.
So, I am trying to build a website that is similar to https://scratch.mit.edu/ and https://www.thingiverse.com/ where there will be an in-site building interface built on JS. This builder will be able to be customized and each sketch saved to a user profile/sketchbook. There needs to be user generated content, user profiles, and a list of all the user posted projects with the option for downloading external files used in the project.
The other part is that the client is really hoping that in the future the project can be picked up and continued on by someone else with relative ease.
Now, I have been playing around with WordPress for the past week trying to get a start on this but I’m noticing that while getting the basic structure is pretty straight forward, as soon as I try to customize or add functionality that would be simple to implement in a scratch-build project, everything becomes much more difficult and much more of a headache to deal with.

So two questions for you guys:
Does this sound like a project that would be right for WordPress or would it end up causing more headache and time than just doing it from scratch?
Has anyone had experience with trying to modify and customize plugins for their specific purpose? And if so, is it a simple process or do you run into immediate or future problems?
Any input would be greatly appreciated.
Thanks