Just wondering about my ''JUST CS'' Strategie

That strategy works against the AI because it makes lots of light frigates, which aren't very good against capital ships.  In fact, they're practically useless until the enemy starts building support cruisers.  By the time the AI gets around to making more advanced units, you can be well entrenched with high level capital ships.  On the other hand, a smart player will move to those higher level unit types, particularly long range frigates and carriers, almost immediately.   A smart player will have the right units and your unsupported capital ships will be dead before you can blink, and you'd be lucky if you even finished construction of your first trade port before you lost your homeworld.

The cost of bringing capital ships out is exorbitant.  In terms of pure damage output and health, you get way better value from basic frigates.  To make that investment in big capital ships worthwhile, you really need to level them up and max out those special abilities.  If you want pure combat power, your money is better spent on frigates.

Facts

"AI never be smarter than human brains"

Human brain can think out of the box, like how should I crack this nut?

Or is there any hole in that well fortify planet?

No matter how good AI is they always run script written from human where script are not human brain which can think.

the issue is more profound than merely the AI building the wrong type of ships or anything like that. what it really goes to the core of is that the AI does not adequately value taking out cap ships before they become criticically dangerous at high level. a human player would build LRMS or carriers with bombers and take out your caps while they're still highly vulnerable at levels 1-3. the AI doesn't register the fact that caps get more dangerous over time so it will let you build up a big force of them until its too late and you can dominate with game-changing level 6 abilities. 

Hard and Unfair AI's cheat just enough to be reasonable opponents against a player who plays conventionally. you'll see them make bad mistakes sometimes, ones that a human probably would never make, but for the most part they'll put up a decent fight. 

the single biggest difference you'll find between facing humans and facing AI opponents is that the human players will basically always focus fire your cap ships first in almost every situation. the AI never does this. thats why they lose horribly to high level cap ships. 

And AI always run whenever your "Small Fleet" get to any planet they are camping at with.

So what u guys tell me is that i should start playing with Frigates???.... what i didnt said in the original post is that i make some Colonize ships as well as scout because they do some jobs that other ships cant (caputre Neutral Extractor and Watching for mines. but that'S pretty much it.

Now ill go with another question if u dont mind.... i want to try something else for the 1st 30 minutes of play. and since i dont know other tactics for a good start

Build as many labs as necessary to research your long range frigate (assailant for Vasari, javelis for TEC, and illuminator for Advent).  Build your best capital ship, maybe capture a nearby asteroid to bolster your income, then fill the remainder of your 100 command points with LRF.  Now attack the enemy.  Obviously you will want to build a few scouts to find the enemy, and this won't work if it's a very long distance to the enemy's homeworld.

The idea is to lead with a hard military offensive, ignoring all economic techs.  You will conquer planets to make your economy stronger, rather than buying upgrades.  You can probably capture a hard AI's homeworld in the first ten minutes of the game, and that's a cash cow!  With practice, this strategy can get you a huge empire very quickly into the game.

Ok..... ill try that... but building LRM that much that soon in the game ... wont be more cosly than building lets say 1 other cap

if the ennemy is that week

2 caps should b hable to crush him right?

50 command of long range frigates will deal far more damage than any level 1 capital ship (with the possible exception of an evacuator using nano-disassemblers), plus they cost less than a capital ship, plus they don't have an expensive upgrade associated with them.  Because of this, you'll actually have a lot more damage output much earlier in the game with long range frigates than you would with capital ships.  Another plus is that your first capital ship gets all the experience, and will reach high levels quickly.