Calculate Average Time between Two Rows in a Range of Many Non-Consectuive Rows

This may be a simple question, but I've been having trouble getting to the end result. I have a spreadsheet of production data that I filter based on the date and the worker. One of the columns, I'm working with is the time that each job was started. So for example:
Confirmation time
8:39:11 AM
8:52:04 AM
8:52:29 AM
9:08:48 AM
9:09:29 AM
9:10:03 AM
9:11:09 AM
9:20:51 AM


I want to calculate the average time between all rows. I was thinking this may be just a simple standard deviation, but the results don't seem right...
The main problem I'm running into is that these rows are not consecutive since the spreadsheet was filtered.

Any guidance or suggestions would be much appreciated.

I feel like there must be a simple answer to this...