Brand new websites can sometimes be subject to the sandbox effect. The sandbox effect is a highly debated observation about the way Google serves relatively poor rankings for new websites in the first months of launch. No observer can seem to agree on whether the sandbox effect even exists, let alone how it operates. Google has been tight-lipped (Google almost never reveals specifics about its algorithm).
What is reasonably certain is that the sandbox effect often doesn't apply at all niches. Brand new sites can rank quite well but typically in less competitive markets. So, if the sandbox effect is being algorithmically imposed by Google, it is being imposed only upon certain categories and niches. It is also possible that the sandbox effect is triggered by some external trigger such as garnering too many powerful links too quickly.
Don't fight the sandbox effect. In the first months of your website's life, you need to build the links slowly. Don't simply rush out and secure...