We've designed Files/Notes to store a wide variety of file types, such as Word Docs, Excel Spreadsheets and PDFs. You can upload files straight from your computer and there's also a function to share links to Google files.
You can start Notes and add them to Projects you're working on or keep them as drafts for later.
Can't find that file that you posted in a comment last week? Just use the Attachments in Comments tab and find it in there.