Is it 100% safe to handle the soil by bare hands? Would any toxic insect hide inside the soils?
No, nothing is 100% safe.
That said, I've always done gardening (from the earliest age), also when working indoors or outdoors, with bare-hands. I don't like wearing gloves, just a personal preference.
Though the above statement is not quite true, as I have worn gloves (and other safety equipment) when:
But "generally" speaking I do not wear gloves when gardening, I find they get in the way, I like to feel what I'm doing...
While out in the garden I will rinse my dirty-hands with cold water from the hose, as and when I feel they need a slight clean.
As soon as I go inside (to have a drink, something to eat, etc), I will wash my hands with warm, soapy water.
Of more concern in the garden would be things like:
Personally in my own garden or a well maintained garden, I really wouldn't worry about such things, as long as common sense and good judgment prevails.
It depends on where you live. Toxic (poisonous / venomous) insects are more prevalent in some places than others.
Where I garden there's only one kind (that I can identify) of biting ant, ground wasps are not common, and there aren't any poisonous spiders or snakes.
In places like the southern US, fire ants are more common. Though I'm not sure how much protection gloves would provide against these or wasps -- the ants will climb right up your arm (or inside the glove) and bite you, and the wasps will fly up and get you where they can (or bite you through your clothes).
No. But it's not 100% safe to walk out your front door in the morning either: there could be a rabid dog in your driveway. Neither is it 100% safe to stay in the house: a large meteorite could fall from the sky, crash through the roof, and crush you as you lounge on the couch.
I garden with bare hands, except when I know I'm going to be doing enough digging to give myself blisters, or when I have to pull out thorny blackberries.
Insects are rarely a problem. The only one I can think of that might bite in soil, would be ants. Also avoid the blatantly obvious like digging into wasp/hornet/etc nests!
I think you are probably thinking of bacteria and other microbes. Generally you will be fine, no problems; but beware of animal (and human) urine and faces contaminating the soil. Also use gloves if you have cuts - this is how tetanus (a virus) spreads. Or just have your tetanus vaccination.