But your images have shadows. The lighting is a bit harsh, but fine for these subjects. It seems like though you might have diffused the light, it is still a relatively small source so it behaves a bit like a very slightly softer than un-diffused light. The reason why I use a large bounce card is to soften the light even more. The shadows in your images have hard edges. A bigger light source would have softer transitions to shadows.
A little post processing would also tame the harshness. But it won't help the "flat lighting"
Regarding light and shadow, 19th Century artist, illustrator and teacher, Howard Pyle, wrote,
"Paint your picture by means of the lights. Lights define texture and color - shadows define form."
"By virtue of shadow all objects of nature assume form or shape, for if there were no shadow all would be a flat glare of light, color and texture…but when the shadow appears, the object takes form and shape. The province of shadow is to produce form and shape, and that of itself possesses no power of conveying an impression of color or texture.”
"A picture is more articulate where the light is concentrated on certain part rather than on all of it."
"In a diffuse light everything is soft and close in tone."
Needless to say the same rules of light and shadow apply to photography. Shadows are good. Light is good. The best artists (photographers) are those who make the balance work.
But your images have shadows. The lighting is a bi... (