If for some reason or the other, because of an emergency, or perhaps craving jail time or did not want her job, or perhaps a girls will be girls moment, a pilot and her captain decided to fly a large aircraft like the A380 or boeing 747 inverted and some passengers decided not to strap on their seat belts per instruction in protest of the girls will be girls stunt, what would happen to the unstrapped passengers if the pilots flew this aircraft inverted for a minute or so at its maximum flying altitude? Would they land on the ceiling, because acrobatic pilots seem not to when they fly inverted. Will this aircraft land safely?
That depends on how the pilot inverted the aircraft. If they pulled a Tex Johnson and executed a smooth barrel roll everyone would remain in their seats as it is a 1G maneuver. Even the flight attendants pouring drinks wouldn't spill.
If the Pilot executed an aileron roll the situation would be quite a bit different...
You don't see aerobatic pilots hit the roof for two reasons:
When aerobatics are planned and intentional, the pilots are strapped in tight by the seat harnesses (usually 4 or 5 point harnesses). During sustained inverted flight, their harness hold them in their seat.
For simple, quick maneuvers, such as a barrel roll, the maneuver can be be done so that the acceleration will always be "down" relative to the airplane (towards the seat), even when the airplane is upside down. This is the same principle as swinging a bucket of water over your head and the water doesn't immediately fall out.
In the case you created, it is possible for a wide-body / heavy plane to do a barrel roll and be inverted briefly so that passengers don't fall out of their seats. Test Pilot Tex Johnson famously did a such a 1G roll in a 707 (although without passengers).
If the flight were sustained inverted flight, however, everyone not strapped down would hit the ceiling.