Hi @PBreezy, welcome to the community 
n8n would always require “column headers” I am afraid as these would represent the keys in the data structure used by n8n. When adding rows to an existing sheet in Google Sheets these keys would also be used by n8n to identify the corresponding columns on the respective sheet. n8n would, however, not add additional column headers to your sheet (if this was a concern for you).
As for extracting the HTML table data itself, I think this would do the job:
This is mostly based on this workflow I shared a while back with some small adjustments to take into account your table structure, using the newer Code node, and using some static data to allow running this workflow directly rather than requiring a specific email to arrive (you would of course need to change the Gmail node back in once you’re happy with the workflow).
This is the result:
Hope this helps!