MC decides to take a break from work for 6 months to travel remote areas. Able to do so due to recent inheritance/life insurance payout from relative's death. Decides to take laptop with solar charger to document travels on a nature blog. Otherwise travels with minimal gear (tent, sleeping bag, backpack, simple cooking gear, a week's worth of food, a knife, a hatchet, a gun with a single box of ammunition, a couple of flares, matches, a few changes of utilitarian clothes). Goes on a few camping trips initially with a more experienced person and enjoys learning tips from them. MC decides that next trip will be solo. First or second night of trip, experiences something (struck by lightning, camped in weird cave, sudden beam of light from overhead, etc - author determined) that results in MC and their gear/campsite ending up in the far past.
Thinking something similar to Scotland-the-Brave's Surviving... but much farther back in time (Bronze Age or further). No special skills (ie not an engineer/historian determined to advance human history by introducing "modern" equipment into a pre-industrial society) just a normal everyday "Joe". Continues to write blog entries (unposted obviously) detailing adventures in past including photos (laptop webcam/phone cam kept charged with solar charger). Manages somehow to return to present and the written entries eventually get posted. The photos included in the entries depict several extinct animals / proto-civilizations that have died out. Bedlam ensues.
Maybe write the whole story as the series of entries posted by the blogger...