Hi, and welcome! 
I’d be looking for things that can generate mana (convert, create, destroy, explode gems), and things that can do lots of damage, repeatedly . Of the troops you’ve listed (thank you for that, btw), my top picks would be Clockwork Sphinx, and then if you get the Alchemist troop, you can make a pretty nice red/yellow combo with Alchemist + Moneylender (not necessarily on the same team as Clockwork Sphinx, they’re just both good options). There are maybe a couple of other things you could do - you’ll want to level/trait out Fire Bomb at some point (not necessarily now); Summer Knight can be an okay tank as well.
Otherwise, I’d put your Hero up the front with the Sword of Heroes, or any other non-mana blocking (i.e. a separate mana colour to your other troops) common weapon, that you’ve upgraded to +5 with common ingots that you get from PvP, for the stat boosts. Then, join a decent guild that matches your level of play (ask in Global 001), and wait until you get some more/better troops (you will get rewards from your guild), and keep playing .
Complete the Forest of Thorns quest line, and you’ll get a decent damage-dealing troop (Rowanne) that will go really nicely with Clockwork Sphinx. You can combine this with the Hero weapon Golden Cog, which requires Red/Yellow mana mastery to unlock, although you may have other options by that point. The troop from Darkstone (Dimetraxia) is okay as well.
To get the souls to level up your troops, start off with the Arena (which you should have unlocked from Broken Spire). It will help if you have one of the better armours (Dragon or Celestial). It can be hard knowing what to pick as a newbie, but if you see any of the following, grab them: Rock Spirit, Ranger, Armored Boar… (I may think of others and add them here, or make a new thread for this). Try to get a mix of colours. Winning all 8 battles will get you 1500 souls, boosted by whatever bonuses you have (armor, guild, etc.).
At some point you can start using soul-farming troops. Search ‘soul’ or ‘soul(s)’ in the troop filter search bar for troops that gain souls in battle (Avina, from the Ghulvania questline gives a good amount at lower levels, and Valkyrie is super useful and can slot into many teams), and search ‘necro’ (short for the Necromancy trait) for troops that boost the amount of souls they gain. Levelling up troops for your teams is definitely one of the difficulties faced by newer players.
Let us know if you need any more help, and I hope that’s enough to get you started!