Other commenters have good advice re software RAID. I’ll just reiterate you should investigate that. TrueNAS is what I use, and it’s great.

I’ll add some thoughts about the application. Is this for professional work, as in, someone is going to be counting on you to forever more have the files you mention available? If so; you have basically just one copy (I think) of the info, that’s what gets backed up in the NAS/RAID. if people are needing this data to be safe and protected against all manner of things that happen to data, you’ll need to consider another backup option, offsite, like a cloud provider. Something like Backblaze, AWS, or Google or something. Another great feature of software RAID solutions like truenas or unsaid is that they make it easy to setup rsync or something similar to automate these cloud (or local) backups for you.

If this is just you trying to make your workflow more convenient, that’s a bit different, but still know you’re a little light on the backup side of things. No matter what RAID type you use, it’s not a backup.