In Challengers of the Unknown #4 (August 1958), it’s hard not to see Jack Kirby angling towards complex, fantastical world-building alongside and team-building between characters, as the Challengers find themselves traveling through time in a scientist’s “time cube”. Very Fantastic Four!
And what I love the most are those giant, single-page splashes, like this one when they arrive in the year 3000:
Kirby left DC in mid-1959 and eventually jump-started the Marvel Age with Stan Lee in 1961, but it would have been interesting to see him being given a greater reign at DC. Green Lantern would have been a natural fit with all the cosmic meanderings.