@SyaninditaSousei no Taiga is probably what you're looking for -- regular guy time-travels to prehistoric age; but, if you're ok with fantasy, The Beginning After The End and A Returner's Magic Should Be Special are also pretty great. Tokyo卍Revengers is another modern-day time travel story, but it's getting a visually-great anime in the Spring, so I'd wait for that.
Also, there's a LOT of good non-action, time-travel manhwa: I'll be the Matriarch, The Villainess Reverses the Hourglass, & The Flower Dances and the Wind Sings are absolutely fantastic stories. A lot of drama -- but it's good quality and not just there to fill pages.