Apple officially introduced iOS 8 in 2014. It’s been 7 years and still, you can use the official iOS 8 with good performances. When moving from iOS 7 to iOS 8 Apple dropped some iDevice compatibility. So you cannot upgrade iOS 8 for iPhone 4 and it begins the compatibility with iPhone 4s. So without any mess, you can use this update, and then the iOS 8 jailbreak download allows you to install third party opportunities without any messing.