a slow shutter lets more light in.
A low iso only requires a low aperture if the light requires a low aperture.
Your shutter speed in the first shot would freeze a hummingbirds wings but its also why the depth of field is so shallow.
Without an IS lens you should be able to shoot at speeds as low as 1/60th handheld which would allow for smaller apertures(bigger numbers), which give more dof.