The Aston Villa striker was an unused substitute as Thomas Tuchel's men beat Croatia 4-2 in Arlington, Texas, in their tournament opener.
Kane, who has enjoyed an incredible goalscoring season for Bayern Munich, scored twice in an impressive attacking display.
"His goal record speaks for itself," Watkins said at England's training base in Kansas City. "I don't think I can really emulate what he does. I think he's unique.
"The way he plays the game is very intelligent and I can't play the game like him, so we have completely different strengths.
"I stick to what I know I can do and I don't try and copy or do anything like that. I just stick to my strengths really."
Watkins came off the bench to score the winning goal as England beat the Netherlands 2-1 in the Euro 2024 semi-finals in Germany.
He was also used as a substitute in the final against Spain, which England lost 2-1, prolonging their decades-long wait for a major title.
"I know what I can bring to the table," he said. "I watch the game when I'm on the bench. I can see the game open up.
"It's a completely different game when you start a game of football to when you finish it. I've experienced that as a substitute.
"There's so many more opportunities when you come on. A lot of people are tired, they lose focus. Sometimes it can be better to be a substitute than to start the game.
"I think the most important thing is when we're not starting the game, when we're on the bench, watch carefully what the opposition player is doing. When you come on the field, you get that opportunity to punish them."
The 30-year-old, who finished the season strongly with Villa, spoke about how he had turned for advice to former England forward Michael Owen, who has told him to be nastier on the pitch.
"On the pitch I think I've definitely taken that sort of element into the games," said Watkins.
"At the back end of the season I think you saw how well I've done and that's why I'm here in this position.
"I definitely felt it helped - there were times where I would say I was maybe a bit too nice on the pitch. He just gave me an insight on how he felt I could improve."
England's next Group L fixture is against Ghana in Boston on Tuesday before they face Panama in their final first-round game.
World Cup 2026
The 2026 World Cup will be held from June 11th to July 19th in the United States, Canada and Mexico. The tournament will feature 48 national teams and will be played in 16 modern stadiums.
Match schedule and times | Group tables | England at the World Cup | Scotland at the World Cup | Team rosters at the World Cup | How to watch the World Cup | Predictions and odds | Which teams could be considered dark horses?