United finished nine points clear of runners-up Chelsea, their biggest margin of victory for more than a decade.
It hardly tells the whole story of an arduous campaign - if the Blues had won at Old Trafford three weeks ago, they would have gone top themselves.
"It sounds easy but it wasn't, nowhere near," said Rooney.
"That Chelsea game was massive. If we had lost that game they would have been in the leading position.
"But we showed our true spirit to win after that, Chelsea's season was over."
Although United led through Park Ji-sung, once more they were forced to delve into their huge reserves of spirit to overcome a Blackpool side who were eventually condemned to the drop.
Anderson netted a second-half leveller before an Ian Evatt own goal put the champions in front at Old Trafford.
Michael Owen made it 4-2 and ensured United head into Saturday's Champions League final confrontation with Barcelona at Wembley in confident mood.
"You never get bored of celebrations like this," said Rooney.
"This is what you play football to do, to win trophies and medals.
"The first half of the season was a bit of a write off for me but since the turn of the year I feel I have contributed.
"We have won games and I have really enjoyed it.
"It has been a squad effort.
"The manager said last week there are 21 players who qualify for a medal, which shows how much we have used the squad and spread the games out amongst the players."
Fittingly, Edwin van der Sar skippered United in his final Premier League game before heading into retirement.
"I would like to thank the manager for bringing me here six years ago," said the 40-year-old Dutchman. "Maybe it was a couple of years too late.
"I have thoroughly enjoyed my time here. The fans, the players and the manager will always have a warm place in my heart.
"Manchester United is the biggest club in the world. Now we have to get that trophy next Saturday."