How can a mobile charger's output current be 1 or 2 Ampere if 1 Ampere is a deadly value for a human, but when I touch the output wire I don't feel anything?
The charger can supply a maximum of 1 or 2 Amps to a low resistance circuit in your phone. That doesn't mean 1amp flows through you when you touch it - you are a much higher resistance.
Whether 1 amp would harm you is also a bit more complicated. 1 Amp of low voltage DC would flow harmlessly over the outside of your skin, you wouldn't even feel the heating effect. At higher voltages 1amp could flow into your muscles causing them to contract, while 1000Amps of high voltage DC from say a subway train would heat you a little less harmlessly
The real danger comes from higher voltage AC, this can travel through your body and interfere with the electrical signals in your heart. As little as 20-30mA can be fatal if it flows across your chest