I circled the tiny speck so you could see him. Any help?
Oh, your problem is that the dimensions of your mesh are tiny! A mere 1.6074cm tall—this is why it is so small in UE4. I would scale the character by about 100 times. A quick way to do this is to type 'S' and then '100' on your keyboard. After which you should apply the rotation and scale at the very least. I usually also apply the transform. Note: make sure you are in object mode and apply the transforms to the armature and the meshes of your character. In Blender 2.79 you have to do it one-by-one.
If you have multiple meshes in blender it can be tricky to measure them all together. One way I do it is by clicking on the top of the character's head: the 3D cursor will be placed there, and then in the right panel you'll be able to see the height of your character. It should definitely be somewhere between 1m - 2.2m tall for a humanoid character.