I hope all is well with you 😄
While there isn't an endpoint that allows you to retrieve all of the contact activity at one go, Connor mentioned a few endpoints here: https://community.hubspot.com/t5/APIs-Integrations/How-to-get-activity-stats-and-details-for-contact... that you can explore to gather those contact activity.
In short, you can:
1. Retrieve all your engagements such as notes, meetings, calls, tasks and 1:1 emails using the Get all engagements
2. For marketing emails events, you can use this endpoint: Get email events | Email Events API
3. Analytics breakdown, you can use this endpoint: Analytics API Overview
4. Form submission data: Get submissions for a form