Since it targets boys, yeah. Anything that focuses on the young male demographic can be considered Shonen. If it focuses on adults and or female demographic , it is Seinen and or Shojo.
Gender of the main character or its focus could be entirely separate, because there can be Shojo with male leads and Shonen with female leads. Though it can be rare at times in such an atypical formula.
Many modern Kamen Riders and much of the Showa Riders fit into this demographic of young boys , though their elements can highly differ depending on whatever. If you mean in its maturity level that is. Then again, the "typical" boys cartoon I believe would fit into the narrative of many modern Riders such as OOO and Fourze.
Why? OOO and Fourze has various elements of Japanese Shonen anime, though Kuuga, Faiz, Blade , and Hibiki have various elements of Japanese drama.