As a “shared” computer, the MacBook can do a lot that an iPad (of any model) cannot do.
A fundamental difference between Mac and iPad is that the iPad is only intended to be a single user device - whereas the Mac is designed to support multiple Users, each User having their own profile. Having multiple user profiles keeps sensitive information (such as logon credentials and passwords, private email and messages, credit card details etc.) entirely separate. An iPad fundamentally does not support multiple users or multiple user profiles.
As much as I would love to highlight features and benefits of iPad, a device for which I have considerable love, I cannot in good conscience recommend that you contemplate an iPad for use by multiple users. You will very rapidly stumble upon insurmountable issues with unintended sharing of information and data - and will quickly become frustrated.
Whilst a Mac can be shared, each user should have their own iPad/iPhone.