No, in that sense it's just a hobby or activity. It's just like comparing real tennis to just hitting a ball against a wall for practice. One is a real sport and the other is just something you can do during your downtime.
Yes. Horse riding is very physical. I don't know how long you rode, but you sound like you are very athletic. It is "easy"... but if you ride for a half hour or more, having not ridden before, you will be sore. The most used muscles are the upper thighs. When your horse trots or runs, you lift yourself off of the saddle slightly, putting weight on your feet and lower legs, and sometimes your upper thighs as your thighs squeeze into the horse for stability. If you are riding correctly and not just sitting in the saddle bouncing around, then yes, it is a sport.
its hard but for some it comes easier than others. also while your racing people go extremely fast, anyway horse riding is a sport.
NO horse riding is not sport.it is just a fun and loving experience.