I only knew Wasinojinsei existed when I was looking for trains to add to someone's document and found many of the videos show what said items look like on the inside. Their videos helped me a lot when it came to that.
Either way: the YouTubers who made me find out how much there really was to Thomas, Plarail, other toy/model trains and (to a lesser extent) LEGO were largely the same ones who attracted other people to those fandoms/hobbies back then. In no particular order:
MissOliverandBlossom
TrainLover476
Trainboy7
CaptainPunjab
Ramahfool
Thomasfan8
EliJBrown
Etenks1
ToyTrains4U
JJSchepis3
Sparkshot
DieselD199
Rexeljet
Topkazfatt
TurboJUK
Simierski
DcolemanH
Tonypilot
CombineHarvester01
TooMuchThomas
NewController01
TomTomica
Cactus190706
Skullzproductions
However, there's one other Australian like Ucwepn who left a much bigger impact on me than all of the above - Leokimvideo. Where do I even begin? I credit his videos for my introductions to Chuggington and Thunderbirds, products like Blu-Tack, cutting mats, GoPro cameras, HexBugs and WD-40, the concept of pyrotechnics (beyond stage fireworks), certain filming techniques and special effects, attention to fine detail in sets, props and models and a plethora of other things. Unfortunately, I also began to impersonate his voice, accent and dialect in ways that would've surely made him furious if I were to meet him. That said, it did help me improve my accent in English after I toned it down in later years.