how did you get from Shannon airport to Ennis?
Bus #51 hourly and direct- https://assets-us-01.kc-usercontent.com/db136e73-39a4-0017-c8cc-5f063ce7fc95/23689fca-e9fc-4eb7-8eea-9610fee10ab4/timetable-51-jun25.pdf
There is also an hourly #330 which goes round all the villages, and takes over twice as long - avoid that one.
We took a taxi directly to our hotel. Cost was about €45 with tip.
You'll be jet lagged and uncomfortable. Take a taxi.
I'm taking the 7 Day Highlight tour next month. Just booked taxi from Shannon Airport to the hotel. 60 Euro. Expensive but I'm arriving in the morning the tour starts and don't want to hassle with my bags on bus etc. I booked through the taxi page on Shannon Airport website and got a reply back within 15 minutes.
Spearsfs, the buses that go from the airport are designed to handle luggage, some with racks inside and some with a "boot" you can put your bags in.