Question

Sharks appear.
Insects appear.
Fishes with jaws appear.
Which of these best orders the events from the earliest to the most recent?

Answer 1

The oldest record of sharks is from ~420 million years ago (but in truth sharks don't often fossilize and most of those fossils would likely be found on basaltic seafloors, not continental plates, so they're possible older), they are truly ancient and one of the few ancient animals still surviving today (which means they are incredibly well adapted at what they do).

The higher tier phylogeny of the arthropods (i.e.: insects) continues to be a matter of debate & research, I would guess about 300 million years ago? Nobody is going to be able to give you an exact answer on that.

Fish with jaws I believe started by the late Ordovician to the beginning of the Devonian, about (somewhere between 488.3 to 420 million years ago) million years ago. Starting with Placoderms to form the classification "Gnathostomata" around 416 million years ago. Very old fossils of jawed fish are being found in China today from the Ordovician period (we can tell because of the rock layers it's in, and because China's quarries are digging deeper these days).

You actually will be hard pressed to find which actually came first, sharks or jawed fish. In truth it probably started at the same time was probably just a successful adaptation for existing vertebrate predators.

Insects however came later. The land wasn't exactly "friendly" towards life during the time sharks and jawed fish started to appear. (read: roasty toasty lifeforms! AAAAH!)