"I'm not saying things are over. But I am saying that the reaction is that people should buy stocks," Cramer said on "Squawk on the Street." "There's are a lot of people who have not been in the market."
U.S. stocks were soaring Tuesday after a 17.7% jump in retail sales during the month of May as the U.S. economy restarted from coronavirus-induced shutdowns. Economists surveyed by Dow Jones had expected an 8% increase.
"I think this is a sign that things are coming back. Just coming back," Cramer said, while criticizing the decisions by government officials to close nonessential businesses in an attempt to slow the spread of Covid-19.
"Look, if we had used masks and we social distanced, this would never have happened. Instead we wiped out a lot of people. Not a lot of stores got to this promise land," added Cramer, calling it a "multiple-trillion dollar mistake."
Wall Street also reacted Tuesday to a study that found a generic steroid drug lowered death rates for patients severely sick with Covid-19 by about one-third. One of the study's investigators called it a "major breakthrough," according to Reuters.
The new study that found benefits from dexamethasone is an indication there is "something that could really help us with this illness, to make it so we get out of the hospital," the "Mad Money" host said.
Cramer has for weeks argued that the country's economy will be in a stronger position when U.S. residents do not have to be concerned that becoming infected with Covid-19 will be a "death sentence."
The major U.S. indexes last week posted their worst week since March 20, due in part to concerns about rising Covid-19 cases in parts of the country.
Cramer acknowledged concerns some people may have about the staying power of U.S. consumer spending during the pandemic, particularly after the enhanced unemployment benefits run out this summer. However, he said he believes the way doctors treat Covid-19 will continue to progress into the fall, helping improve the economic outlook as a result.
"It's a new world," he added later. "Look at all the green. ... It's buy, buy, buy."
Correction: Wall Street reacted Tuesday to a study that found a generic steroid drug lowered death rates for patients severely sick with Covid-19 by about one-third. An earlier version misstated the day.