The Reds have added just youngsters Sepp Van Den Berg and Harvey Elliott to a squad which won the Champions League and finished second to Manchester City with the third-highest points total in Premier League history.
There has been criticism of Klopp for not making a significant signing in order to help his side’s quest for a first domestic title since 1990, but Henderson said that was unwarranted.
“If the manager hasn’t signed anyone then he knows better than everyone else,” said Henderson.
“I think we’ve got a fantastic squad of players, we’ve showed that. We can use everybody, we’ve got big players (Naby Keita and Alex Oxlade-Chamberlain) coming back from long-term injuries, which is like new signings as the manager says.
“We believe we’ve got a strong group in the changing room, a strong team, and we’ve just got to keep learning, keep improving on the training pitch, keep doing what we’ve been doing for a long time now, and keep staying hungry for more success.”
Liverpool lost to City on penalties in the Community Shield, but their second-half display suggests they can challenge the reigning champions this season – which gets under way on Friday when the Reds host Norwich.
Having been second-best for the opening 45 minutes at Wembley, Liverpool bounced back after the break and were the better side.
And they could have snatched victory in added time had Mohamed Salah’s header not been acrobatically cleared by Kyle Walker just inches from the goalline.
“We were much better in the second half,” added Henderson.
“I thought we played really well, back to what we know that we’re capable of. So a lot of positives to take from the game.
“I thought we created some great chances, Mo created some really good chances to score (and was) a little bit unlucky not to score the header at the end.
“But it was really positive stuff and we take that going into the game Friday.”
Liverpool finished with 97 points last season having lost just one match and they will have to maintain similar standards to have a chance of usurping City.
However, Henderson stressed the quality of the performances rather than the points tally was the one thing which would improve.
“We can’t always think back to what we did last season. We’re looking forward, we want to improve as a team,” he said.
“There were a lot of games last year where we didn’t play particularly well and play as well as we like and we did grind results out at times.
“Performance-wise we can be much better and that’s what we’ve got to focus on. Performance has got to be improving all the time.”