From the link, they mostly look like vector-based 2D animation. Adobe Animate and ToonBoom are the ones you will have to look into. Tupi is also available for a free software but I have never used it so I am not sure about that.
As far as the best software to learn animation easily goes, I would suggest Pencil2D, lightweight and you start animating as soon as you start the software and no need to spend a lot of time in just learning about the software. But as of now, Pencil2D is still a bitmap based animation, even though it has vector tools, but it needs quite a lot of improvement.
Usually, making an animated film or shorts requires a combination of software: like Adobe Animate(the animation software), Adobe Audition(sound recordings and anything related to sound), Adobe After Effects(the compositor, where the animated frames all come together) and Adobe Premier Pro(the video editor to make the final clip).
My version of free softwares would be Pencil2D, Audacity(sound), Natron or Fusion Lite(Compositor), and for a video editor, either Blender VSE/Kdenlive/Shotcut/Openshot/Da Vinci Resolve(require high-end PC for the last one).