Howdy Tomhip
from > Change your Apple ID - Apple Support
Learn how to change the email address that you use as your Apple ID.
In most cases, your Apple ID is also the primary email address of your Apple ID account. You can change your Apple ID to any other email address you control, as long as it's not already in use as an Apple ID. If your email address ends with @icloud.com, @me.com, or @mac.com, it's already an Apple ID.
The way I read this is that - Yes, you can use a "pre-used, but NO longer being used" email address as a Primary Email Address.
IF, the system is not allowing the use of an email address you control, it is either:
- making an error die to some snafu in the database
OR
- it IS being used as another Apple ID
From this Welcome page > https://www.apple.com/support/appleid/ , choose Contact Support from the ToC on the left to get started in the process - in 'context' of Apple ID
Change your Apple ID
Learn how to change the email address that you use as your Apple ID.