I don't understand what you're confused about here.
Seriously, some of you guys are overthinking it.
The flashbacks were what happened in the timeline when the team was not brought into the future. And now when they go back to the past, they will need to prevent that bad timeline from happening completely.
That's it.
The flashbacks are of the timeline they're currently in. They are Robin's memories of what has happened in between the timeskip. I had explained earlier that they can't be in the future of an original timeline in which they never jumped through time because otherwise Fitz couldn't have caught up with them by waiting it out in a cryochamber.
So currently there is a time loop paradox going on. Obviously this will be changed because AoS can't just fuck up the MCU's future.
Here's the chain of events in chronological order:
- Diner scene
- SHIELD jumps forward in time. The 2017 versions of the characters disappear from the timeline for ~70 years
- Fitz gets left behind, wants to rejoin them
- Fitz gets Enoch to help him, gets put in cryosleep in space. He leaves behind a note on a postcard: "Working on it"
- While Fitz is in space napping, the Earth breaks apart. SHIELD is apparently at ground zero. The Zephyr records footage of Daisy leaving a Quinjet shortly before that. Daisy jumped through time though and should be gone so unless this is an impostor, clone or LMD, this has to be Daisy who returned from 2091.
- Post apocalypse, people take shelter in the Lighthouse as well as the Zephyr. Kree appear and take over etc
- at some point the footage of Daisy is discovered on the Zephyr's harddrives
- May raises Robin. May should also be gone because of the time jump yet here she is. Again, unless LMD or otherwise, this is May who has returned from 2091
- Fitz working on the time machine on the Zephyr. This is a second Fitz, the one from 2017 is still sleeping in space.
- fast forward to 2091, the time machine has been activated to trigger the monolith in 2017. Timejumping SHIELD from 2017 finally reappears in the Lighthouse.
- they find Fitz' note
- Fitz himself finally gets woken up
- shit from recent episodes happens
- Voss shows Daisy the footage of herself and tries to kill her to prevent her from going back and being the alleged cause of the apocalypse
- Robin dies and tells May she raised Robin as well as how to get back
-> so now they're eventually going back in time and unless something changes, they would just repeat what has already happened and prove Fitz' theory that time is fixed. Obviously something will change and the question now is what that is and how the team will figure that out.
So while it's probably going to end up with alternate/split or overwritten timelines or whatever, everything we have seen so far is from one and the same timeline. If there was an original "no timejump" timeline, we haven't seen that.
Imo. :P