Hi guys,

Can I use 2 WANs in the same interface (e.g ether1) simultaneously?
And if that's possible, can I then route traffic in the ip/routes section through WAN1 or WAN2 according to my needs?

Thanks in advance

Yes, it's possible but not recommend.
Best way if you can use separate VLAN at this ether1.

Please read this HowTo from Tomas at MUM:

Bandwidth-based load-balancing with failover. The easy way.
https://www.youtube.com/watch?v=67Dna_ffCvc
https://mum.mikrotik.com/presentations/US12/tomas.pdf

Hmm, well thank you for the advice, but I need to know how can I accomplish my topic question... Can you explain more pls?

Routing have "default gateway" means address 0.0.0.0 per some interface.
You can have two IP subnets at the same interface and proper default gateway by properly IP addresses and you reach your goal.

I present you a HowTo in presentation and description in video, what else you have answers?

That I should ask you how this possible to have both ISP connected by shared one interface? If your ISP are connect to switch and you must connect one patchcord to MikroTik then replace this switch to managed one and use vlans to separate ISP.