How to handle credit
Paperwork is important.  Beyond a simple Excel spreadsheet, you should have appropriate releases from everyone involved in your project.  Depending on your jurisdiction, it is likely that you can't make commercial use of someone's likeness without their consent, and if they decide they don't like your project for some reason they could force it to be taken down until you can edit them out of it without a release.

Similarly, for crew, by default, copyright sits with the person producing the work in most jurisdictions, unless there is an agreement otherwise or there is an employee relationship.  You need agreements with everyone from the project and you need to keep these organized so you can present them if necessary.

Yes, having a master list somewhere like Excel or in a text file is helpful for being able to more quickly add them to the credits, but you need far more than just a simple list of names to properly document a project.