... it was not their to select ....
consider yourself lucky, IMO.
Sorry, but have you really considered the time involved in this excursion from Cozumel.
Have you accounted for all the time. Have you consulted a map?
How are you with sea sickness.
The ferry across the Cozumel channel is notorious.
Not only for the vessels, but the unpredictable seas.
Search videos.
FWIW; IME;
20 minutes with noise to ferry;
20 minute boarding ferry
45 minute channel crossing
15 minutes board bus to CI
120 minutes min to CI
2 hours maxs on site at CI. Likely 90 minutes. As recently posted.
120 minutes ride back to ferry
15 minute ferry boarding min.
45 minute crossing
15 minute debark ferry
20 minute noise back to ship
So;
3:40 travel to Chichen Itza
90 - 110 minutes on site
3:35 travel back to ship.
7:00 hours travel and whatnot for 1 to 2 hours on site.
Only you can decide.
You could fly into Cancun or Merida for a more thorough visit.
JMT
https://disneycruise.disney.go.com/port-adventures/cozumel-mexico-chichen-itza-mayan-ruins/