Why similarities among organisms led scientists to believe that organisms are evolved?
I will answer by explaining some misconceptions in your original question:


  Theory of evolution states that organisms are evolved into other more advanced ones over time


Nope that's not what the theory of evolution is stating, mainly because the expression "more advanced" does not mean much and also is a loaded expression. You might want to start with an intro course to evolutionary biology to understand what the theory of evolution says. Understanding Evolution is a very introductory course you might like


  @Remi.b Alright I will have a look at what theory of evolution states but the basic thing is humans are thought to have evolved from chimpanzees. What I want to know is chimpanzees might resemble to humans but why chimpanzees are considered ancestor of humans? It might be possible that humans and chimpanzees created individually?


No, the theory of evolution does not state that humans evolved from chimpanzees. It says that humans and chimpanzees / bonobos have a common ancestor (about 6 millions years ago) that was not a human, nor was it a chimpanzee or a bonobo.

You can find an introduction to phylogenetics in this post and you can find online tools to visualize the tree of life in this post.

Philosophical issue in your question

The theory of evolution makes predictions that have been tested and demonstrated correct. You are asking why would creationism would not lead to the same predictions. For this purpose, one need to know what predictions would creationism make but this is very much undefined. If you can point to specific predictions that creationism would make, then we could tell you whether we have a counter evidence. The issue is that there is always a way to say, everything has been designed so that it looks like evolution is at play even if species were created anew. But this is not falsifiable. 

So, maybe you might want to make specific predictions, that in your opinion, would be congruent with creationism but not with the theory of evolution and then we can tell you if we have evidence to support this prediction.

Related posts

While it does not directly answer your question (because IMO, for semantic issue, the question is unanswerable), you might want to have a look at Is evolution a fact? and Demonstrable and repeatable examples of evolution