While the game may feel linear from a casual play through, the speed running community have developed many sequence breaks (intended or not), to finish the game

While the game may feel linear from a casual play through, the speed running community have developed many sequence breaks (intended or not), to finish the game faster. With these you can grab items early, out of order, or not at all. If you were curious, you should look up a super metroid speedrun on youtube. Some of them even have a running commentary of glitches, techniques, or general information while they are being played.