Liverpool captain Henderson has returned to pre-season training after helping England reach the World Cup semi-finals.
But with the 28-year-old given an extended break following Russia 2018, Liverpool have thrived in his absence, crushing Napoli 5-0 in Dublin on Saturday, while they also overcame Premier League rivals Manchester United 4-1 in the International Champions Cup.
Klopp, though, insists the midfielder remains in his plans for the 2018-19 season, with Fabinho and Keita's signings addressing the loss of Emre Can to Juventus.
"Hendo is so important to us, not only as a player but also as a person and as a leader," Klopp told the Liverpool Echo.
"You need these players like Hendo and Millie [James Milner] to help create a special spirit in the squad, otherwise it doesn't work. There are no doubts about Hendo. I didn't need the final proof in and around the World Cup or in last season.
"He had to learn kind of a new position for him. I still remember the Burnley game [at Turf Moor in August 2016] when we lost 2-0 with 80 per cent possession. Hendo for sure was involved in the first goal with a press ball that he didn't win. One of the main things I was asked about after the game was: 'Can he really play as the No. 6?'
"I said: 'Yes, he can and he will.' He had to learn and he had to improve and that's exactly what he did. He can still play as the eight or we could play some games with a double six, Fabinho could play the eight or whatever, that's all possible.
"If things were fixed with just one line-up and all the others were only needed when the rest are ill that would be the wrong way and we'd have no chance."
Look who was back at Melwood today. pic.twitter.com/hftlvKDUhm— Liverpool FC (@LFC) August 5, 2018
"What we've tried to do during this transfer window, and during the last few as well, is to widen the squad, to widen the quality," Klopp said.
"I really love our young boys, I really love them. But it's always in difficult moments in a season that you need them. It's so important that you are prepared for the times in the season when it is really intensive, like in January.
"If someone wants to see it in a difficult way – maybe August and September before the Champions League starts, before the EFL Cup starts – one or two players might think they don't play enough, but after that we will need them all constantly.
"If you have played 40 games at the end of this season that would be brilliant, not 50. Most of the boys probably played around 50 games last season but 43 or 44 would be perfect.
"Then you can keep the level really high. I am completely happy with the choice I have in this squad and Jordan will play a very important role."