Without jailbreaking the Firestick, you're limited to installing apps available in the Amazon App Store. There are plenty of great apps in this official channel. Sadly, they are limited to the marketing giant's idea of what is best for Amazon profit margins.
By taking control of what apps you can install on your Fire TV Stick and using a VPN, you safely gain access to the entire catalog of free Android apps. This includes everything you can find in the Google Play Store. There are also a wide range of apps to install developed specifically for jailbroken Firestick and Android devices such as Kodi.
Essentially, if you're satisfied with what's available in the Amazon App Store, there is no need to jailbreak your Firestick. If you want control of your own entertainment channels, you may want your Fire Stick jailbroken.