Buttler, who resigned as captain in February following a wretched 18-month run of results, will keep wicket and bats at number five.
On Buttler, arguably England’s greatest white-ball batter of all-time, being freed of the captaincy, Brook said: “That weight will be lifted off his shoulders.
“He’s the best white-ball player in the world. He can just go out there and showcase his skills.”
Under Buttler, England won the T20 World Cup in 2022, then endured awful campaigns at the 2023 World Cup, 2024 T20 World Cup and the Champions Trophy.
England have lost their past seven ODIs.
“It’s a new era now; new leadership,” said Brook. “Hopefully we can bring a lot of energy, competitiveness and a lot of fun out there.
“We’ll try to engage the crowd as much as we can and try to get some wins under our belt.”
England’s poor run has left them in danger of missing out on automatic qualification for the 2027 World Cup.
Brook’s side are likely to need a place in the top nine of the world rankings in March 2027 in order to avoid going through a qualifying tournament. They begin this three-match series in eighth, one place ahead of West Indies.
The Windies, who did not qualify for the most recent World Cup, drew a three-match series in Ireland 1-1 last week.
“It’s a fresh start and a different series,” said West Indies captain Shai Hope.
“World Cup qualification is our main goal, but we can’t get to 2027 without ticking each box.”
Bethell returns to international cricket after missing the Champions Trophy through injury and skipping England’s Test victory against Zimbabwe because of his IPL commitments.
The 21-year-old, who will line up on his home ground for Warwickshire, was born in Barbados and caught the attention of Hope as a teenager.
“I saw him during his under-15 stint. He always looked like a quality player,” said Hope.
“Seeing what he’s done, he’s certainly a formidable talent. He can go a very long way.
“I’m happy for him, but we’re enemies this time.”
