Diogo Jota and Mohamed Salah struck the goals for the Reds.
McKenna later said: "Irrespective of how the game went today, it would have been a great occasion for the football club to have Premier League football back at Portman Road for the first time in 22 years, it was always going to be a great occasion and I think the performance especially in the first half was something to be really pleased about and a real good base for us to build on in the season.
"I thought in pretty much all aspects, our pressing was really good, we regained a lot of balls high. We were aggressive, we were physical, we built with the ball. We went into the top line and gave Liverpool problems with the physicality that we have. There is a real good base for us to build there.
"We know it is going to be a challenge to keep improving and have to do that for longer in the game. In the second half Liverpool were the much better team and for us to challenge, is to try and build on that first half performance, take the the good things and try and maintain them for longer in the game and learn our lessons from the second half and improve on them week by week."
On two chances in the first half, McKenna stated: "Not just the chances, probably we end up with the shot but also big moments and big opportunities on transitions and things as well. I thought we were the more dominant team in the first half. We know where we have travelled from, seven of the starting 11 were with us in League One so for them to be playing against Liverpool on the first day of the season and be in the ascendancy for the first half and probably the better team in that period, that's a great reflection of what we have achieved here but we'll also look at the second half and continue to find ways to improve and manage that bit of the game better but for sure I feel like there are a lot more positives out there today than negatives.
On conceding two goals in five minutes, he reflected: "It's a key period in the game for us. We showed full commitment and good body language and put bodies on the line when they needed to. We can learn from that. After the first goal, Liverpool were in the ascendancy and their front three clicked into gear. We were a yard off on our pressure and we probably went and chased the game a bit too early to be honest. We probably could have been a bit more closed in that five or 10 minutes. I've got no concerns about the character that we showed on the pitch and in the crowd as well we know we are going to have difficult moments and we faced them head on and we stuck at it and we still played our football until the last whistle."