After being closed for 163 days by the coronavirus pandemic, the British Museum on Thursday became the last of Europe’s major museums to welcome back visitors.

As at other institutions these days, there were hand sanitizer stations and one-way routes, a limited number of visitors, and many masks. But the museum has made some more permanent changes, too.

Hartwig Fischer, the museum’s director, said in an interview that the killing of George Floyd by Minneapolis police in May, and the subsequent Black Lives Matter protests around the world had “altered the awareness of everybody.” The events made him want to intensify the museum’s work addressing its links with slavery and colonialism, he said.

The museum made two main changes for the reopening, Mr. Fischer said. The first was moving a bust of Hans Sloane — a physician and collector of curiosities whose holdings formed the basis of the museum when it was founded in 1753 — from a plinth in a prominent gallery to a display case. Now Sloane is no longer simply celebrated as a natural history collector, but labeled a “slave owner.” The vitrine contains other objects related to Britain’s involvement in the slave trade.

The second move was the creation of a guided route around the museum called “Collecting and Empire,” with plaques that explain how certain items, like a bark shield from Australia, had made their way into the museum. (The plaques stress that most of the items were bought or donated to the museum, not stolen.)

“Our task is to elucidate the history of this institution, and the history of every object in it,” Mr. Fischer said about the alterations. “Openness is really at the heart of this.”

The changes he announced may seem small, but they caused a stir in Britain this week.

The decision to move the bust, which Mr. Fischer first outlined in an interview with The Daily Telegraph, a conservative newspaper, angered some traditionalists. Save Our Statues, a campaign group, said on Twitter that it showed “such disrespect & ingratitude to a man whose generosity has helped preserve so much world history for millions to enjoy.” Other Twitter users pointed out that Sloane had not owned any slaves himself, but that his wealth came from plantations owned by his wife.

Mr. Fischer said he does not use social media, adding that he was aware of the fuss, and that he stood by the decision. People will always complain, he said: “You just have to do the right thing.”