These recommendations are shows that my kids have watched and enjoyed. They've gone through many phases and sometimes return to shows they used to watch. I would have loved to find more shows made originally in Spanish, but in general they're all translations. There are many other options for different tastes! You can always check if there's an audio version in Spanish on any of these streaming services of whatever show your kids like. Many shows have Spanish versions now.
Pocoyo (Netflix - Peninsular Spanish only)
Waffles and Mochi
Robocar Poli
Titipo
Trash Truck
Go Go Cory Carson
Octonauts
Corre Perro Corre
Bluey
Handy Manny
Firebuds
Tumble Leaf
Super Wings (Peninsular Spanish only)
Pesti y Polvi (Stinky and Dirty)
Daniel Tigre
Alma’s Way
Blippi “en español”
Peppa Pig “en español”
Rockalingua - This site has songs with helpful videos as well as lots of other fun materials for learning Spanish
Maná
Juanes
Shakira
Bomba estereo
Los Bacilos
Juan Luis Guerra
Ricardo Arjona