Hello,
Normally your domain would only have one A record which resolved to the place where the domain is hosted. With the additional A records your domain could potentially be resolving to any one of them, if they're all valid and point to the site at Squarespace then it's fine.
For mail, you need to change your MX record to reflect where mail is delivered so if that's the cPanel server you'd need to create an a record for mail.domain.tld where DNS for the domain is hosted that points to the IP address of the mail server if that's the 208.76.80.xx IP then it's listed incorrectly in the DNS zone file. Once the A record is created you need to change your MX record for the domain to point to mail.domain.tld so mail is delivered to the right server.
You'll make these changes where DNS for the domain is hosted, you can normally identify this by which nameservers the domain is using.