The original question is how to stop HubSpot from logging all emails I RECEIVE in Gmail, not emails I SEND in Gmail. Please help me stop HubSpot from logging every email I receive.
I believe that you've connected your Gmail inbox to the Conversations tool in HubSpot, where this is expected behaviour:
If you connect an email with the team inbox in Conversations, every incoming email will get sent to HubSpot & will show up under Conversations > Inbox and on the associated records. You can read more about this type of inbox connection in this help article.
In order to stop all incoming emails getting sent to HubSpot's Conversations inbox, you'd need to disconnect your email in Settings > Tools > Inboxes:
After that, you can connect your inbox with HubSpot as a personal email (Settings > General > Email > Connect personal email), which gives you more control over which emails get logged and which not, especially if you're using the HubSpot Sales Chrome extension.